Production of magnesium and nitric oxide



Feb. 18,, 1947. T. K. HOLMEN PRODUCTION OF MAGNESIUM AND NITRIC OXIDEFiled June 21, 1945 7* INVENTOR.

i L mb Patented Feb. 18, 1947 UNITED STATES PATENT.

ICE

Tor-leif K. Holmen, Brooklyn, N. Y., assignor of twenty-five per cent toMagnus Bjorndal, Jersey City, N. J.

Application June 21, 1943, Serial No. 491,622

2 Claims.

This invention relates to a method and apparatus for producing nitricoxide and magnesium.

The main object of the invention is to produce magnesium from magnesiumoxide (MgO) or other mixtures containing the same, such as calcined lime(MgO+CaO) with which should also be mixed other substances adapted toabsorb oxygen such as magnesium silicide, ferro silicon, etc., by theuse of nitric oxide (N) gas, the mixture containing the magnesium oxidebeing placed in a retort and subjected to the hot nitric oxide gas. Thenitric oxide does not readily give up its oxygen and in fact has atendency to pick up other oxygen to form N02. The nitric oxide is thus areducing, rather than an oxidizing, agent so that if any of it should byany chance seep into or penetrate the retort wherein the magnesium isproduced reoxidation of the magnesium would not occur such as would bethe case if the heating gas would readily give up oxygen. The use of thenitric oxide makes it possible to use a non-metallic retort which may beto some extent porous. The entry of the nitric oxide into the magnesiumproducing retort might even be of advantage in facilitating theproduction of the magnesium by combining with oxygen in the retort toform N02 as referred to.

A further object of the invention is to utilize the heat for formingnitric oxide from air, for causing reduction of the magnesium oxide, thenitric oxide being obtained as a by-product of the production of themagnesium.

A further object of the invention is to provide an improved means forestablishing and maintaining the electric are employed in a producer ofnitric oxide from air.

A further object of the invention is to provide a more efficient actionof the electric are upon the air in a producer of nitric oxide from air.

A further object of the invention is to provide an improved structure ina retort producing magnesium from its oxide which shall lessen orprevent the danger of burning of the magnesium and perhaps otherproducts, at the mouth of the retort upon access of air thereto as whenthe reits oxide which shall facilitate the removal of the magnesium fromthe structure upon which it is deposited.

Other and ancillary objects of the invention will appear hereinafter.

In the accompanying drawing which illustrates the invention Fig. l is adiagrammatic view embodying the invention of means, and by which themethod can be carried out;

Fig. 2 is a section, partly broken away, and on an enlarged scale, onthe line 2-2 of Fig. 1;

Fig. 3 is a transverse sectional view on the line 33 of Fig. Land on anenlarged scale, of the sleeve through which air is admitted to theinterior of the apparatus;

Fig. 4 is a side elevation of the sleeve of Fig. 3;

Fig. 5 is a side elevation, partly in section, and on an enlarged scale,of the lower electrode of Fig. l; and

Fig. 6 is an axial section, and partly in side elevation, on an enlargedscale, of the exit end of the retort.

Referring to the drawing, the apparatus comprises an outer casing 29 ofsuitable refractory material within which the air is subjected to theelectric arc. Lining said refractory casing is a metal sleeve l of whichthe inner wall tapers inwardly adjacent its lower end, the oppositewalls approaching each other most closely at the oil'- cular line 39,the walls then tapering outwardly progressing downwardly from the line30. Just below the line 30, and centrally located, is the end of thecentral electrode comprising the metal pipe I, to the upper end of whichis secured, in good electrical connection, the metal block 3i. Thiselectrode is suitably insulated and mounted in the cap 2 closing thelower end of the electric furnace.

At the upper portion of the casing 29 is mounted a metal ring 33 inwhich is supported the metal tube 5 extending downwardly within themetal lining i into proximity to the taper of the lower end thereof, thering 33 closing the end of the space between the casing 29 and the tube5. The ring 33 and the metal lining 4 are electrically connected toground at 35. An alternating current generator of voltage and capacityappropriate to maintaining the are under the conditions as hereinafterdescribed, has one terminal connected with the ground while the otherterminal is connected through the conductor 3 with the electrode l.

A fan or blower I3 forces air from the atmosphere through an injectornozzle 12 in the intake pipe ill into the annular chamber l between thewall of the cap 2 and the sleeve 8 whence the air passes through thetangential slots 36 in the sleeve into the interior of the furnace aboutthe electrode l Thence the air passes upwardly through the throat at theline 3! Thence, still passing upwardly, the air current divides, oneportion passing between the lining 4 and the tube 5 and the otherportion passing within the tube 5.

Adjacent the top of the furnace but below the upper end of the tube 5there is connected with the area outside the tube 5, an outlet pipe illwhich passes through the cooler H and connects with the intake pipe illabove referred to. The pipe H) has an outlet 3? controlled by a valve ordamper 33 and also has below the outlet 31, a valve or damper M wherebyflow through the pipe Hi may be throttled. Connecting the pipe Ill withthe tubular electrode I is a pipe it which may be more or lessthrottled, by adjusting the valve 39. At point 453 the distance betweenthe electrode block 3| and the metal lining 4 is the shortest and shortenough for an electric arc to form by the prevalent potential. Theuprushing air will force the arc upwards until it connects with tube 5an arc or flame of a cylindrical or conical shape at 49'. The flame willcontinue up the tube 5 for some distance as the air (N-l-O) is convertedto (NO) and the ionized gas forms a conductor.

The gases within and about the tube 5 pass into a suitably heatinsulating and refractory container chamber ll whence they passoutwardly through the pipe 52. A portion of the gases are drawn from thepipe 12 through a pipe 48 by means of a rotary pump or blower 44, thepipe 43 passing through a cooler 45. The blower is impells the gasesthrough a pipe 55, controlled by a valve 45, to a tubular ring 4"!adjacent the upper end of the tube 5, the ring 47 having perfcrations d8upon its inner side whereby the gases from the pipe 45 are sprayed intothe gases passing out of the furnace.

The air passing from the pipe it! through the tangential slots 36 willbe given a swirling rncti on as it is forced upwardly within theproducer, the swirling motion causing the air to more definitely seekthe outside of the producer chamber. An arc having been establishedbetween the central electrode I and the electrode having the apex 3d,the natural tendency for the arc to rise will be greatly added to by theupward current of air when the arc will travel upwardly along theelectrode last referred to and passing its peak at the line 3-6 willthen travel along its upper taper until it finally jumps to the bottomof the tube 5. The taper on the lower side of the electrode is of greatimportance. If this taper were not present, when the arc was originallyinitiated, and before it was well established, the upward current of airwould tend to blow out the arc and it might be diilicult to establishit. With the taper, however, the blowing upward of the arc does notmaterially increase the arc gap until the arc has been thoroughlyestablshed. There is a current of air entering through the electrode lwhich also tends to blow the arc upwardly, and the are or flame travelsup within the tube 5 for the greater part of the length of the tubethereby increasing the efficiency of the action in producing the desirednitric oxide. The upwardly moving air below the end of the tube 5divides into two portions, one portion passing within the tube and uponwhich the arc acts to produce the nitric oxide. The other portion passesbetween the casing 29 and the tube 5 thereby cooling the tube so as toprevent it from,

injury, the gases between the casing and the tube finding an outlet intothe pipe Ii] whence they may be suitably disposed of. In this case, asbefore described, a certain amount of these gases may pass through acooler i l and return into the producer along with outside air. The airwhich enters the producer through the electrode l tends to balance thepressure in the furnace so that the'cooling air traveling upward nearthe inner wall of the casing has less tendency to travel over towardsthe center and thereby form any currents that will mix the cooling airwith that in the arc. Furthermore the air from this central tubularelectrode will travel into the center of the are so as to be surroundedthereby and thus cause the heating of the air by the arc to be moreefllcient and therefore better results be obtained in the production ofthe nitric oxide. The extended and intimate contact of the air with theare within the tube ii is productive of the greatest efficiency inproducing the nitric oxide.

On emerging from the upper end of the tube 5, gases produced by theproduction of nitric oxide in the tube 5 described, will be cooled bythe cooler gases sprayed into them from the ring ll and thus the gasesare cooled down to a temperature at which the nitric oxide is almost, ifnot entirely, non-reacting and which temperature is also suitable forthe purposes of producing the magnesium. The temperature of the gaseswithin the tube 5 is very high, probably 3600 F. to 4000" E, and theyare cooled as described on leaving the tube to a temperature ofapproximately 2000 F.

.1 the chamber ii extends a retort 49 within which the magnesium oxideis distilled by the heat of the gases surrounding it in the chamher. Theretort extends outside the chamber where it is provided with a jacket51! through which is circulated cooling water or other suitable liquid,this cooling causing condensation of the vapor or" magnesium or othermaterials which may be present. The vapors of magnesium are drawn intothe outer cool end of the retort by applying suction to the outer end ofthe retort by means of a pipe 5i controlled by a valve 52. The outer endof the retort is closed by a removable cover plate E3. The mixture 56or" the material containing the magnesium oxide is charged into theheated end of the retort 49. The retort is then evacuated to a highdegree of vacuum by applying suction to the outer end of the retortthrou h the pipe 5| controlled by a pipe 52 by means of evacuating means56 adapted to exhaust relatively large quantities of air quickly andmeans adapted to evacuate the small amount of remaining air to produce ahigher vacuum, the last means being connected to a pipe 5'! controlledby a valve 58.

The tapered collector sleeve 58 for the magnesium is made tapering forthe reason that when the magnesium condenses and deposits on the sleevethe mass traveling toward the retort outlet is reduced and tends to forma higher vacuum at that point which will retard the forward motion oithe other gases. The decrease in diameter due to the taper will offsetthat effect and the deposit on the sleeve will be more uniform. Alsoafter the removal of the sleeve from the retort, the removal of thedeposited magnesium is facilitated, this being accomplished by pushingor knocking the magnesium out of the sleeve through its larger end.

When the outlet end of the retort is opened, by removing the plate 53,for the removal of the magnesium and residue, the influx of air isliable to cause the magnesium to catch fire with undesirableconsequences. To avoid this the inflammable substances are removedduring the process of forming the magnesium and before the retort isopened. This is accomplished by providing a funnel-shaped hood adjacentthe end of the collector sleeve iii, the apex being connected by a pipe22 passing through the cover plate, connected with a source of suctionand controlled by means of the valve 5 5. The funnel is provided withone or more pipe connections 2| opening into its interior and connectedwith a pipe line 26. This pipe line leads to the atmosphere and isprovided with three valves 23, 24 and 25. The valves 24 and 25 arelocated a certain distance apart so that the pipe between them containsa certain and limited quantity of air,. If now the valve 24 is opened asmall quantity of air will be sucked into the hood 29 through the valve23 which may be a needle valve or of other type which can be finely andaccurately adjusted. The chemicals Within the hood 20 will combine withthe air thus admitted and be drawn out through the suction or vacuumpipe 22. By closing the valve 24 and opening valve 25 a fresh charge ofair may be admitted between the valves 24 and 25 when the valve 25 maybe closed, the valve 24 opened and the process repeated as often asnecessary to remove the inflammable materials collecting within the hood20 so that upon opening the retort there will be no catching fire asbefore referred to. The method of admitting the air to the funnelthrough the pipe 20 for the purpose as indicated, insures that therewill be only a limited supply of air admitted to the hood and that theinjurious consequences of an inrush of excess air are prevented.

The magnesium of a charge having been deposited on the collector sleeve,this is removed by removing the closure plate at the outer end of theretort and then removing the collector sleeve. The magnesium is thenremoved from the sleeve, another charge may be placed in the retort, thecollector sleeve and end closure plate be placed in position and theoperation repeated. This repetition may continue indefinitely.

While the invention has been illustrated in what is considered its bestapplication it may have 6' other embodiments without departing from itsspirit and is not therefore limited to the structure shown in thedrawing.

What I claim is:

1. A method of producing magnesium as a by product in the production ofnitric oxide from air by the electric arc method comprising the steps ofintroducing the air under pressure through a hollow electrode, heatingthe air by means of an electric arc to a high temperature, ionizing theair by means of thermal agitation as well as by the potential field ofthe arc, conducting the air from the arc to a magnesium retort andcooling the air by contact with said retort whereby sumcient heat forproducing magnesium is obtained from the waste heat of th nitric oxideprocess.

2. A method of producing magnesium as a byproduct in the production ofnitric oxide from air by the electric arc method comprising the steps ofintroducing the air through a hollow electrode. heating the air by meansof an electric arc to a high temperature, ionizing the air by thermalagitation as well as by the potential field of the arc, conducting theresulting gases from the arc, controlling the temperature of said gasesand letting said hot gases impinge upon a magnesium retort therebyutilizing the heat of said gases and cooling same for the stabilizationof their nitric oxide content.

TORLEIF K. HOLMEN.

REFERENCES CITED The following references are of record in the file ofthis patent:

Industrial Electro-Chemistry, Mantell, 1931. McGraw-I-Iill Bk. 00., N.Y., page 472. (Copy in Div. 56.)

